1. Field of the Invention
This invention relates to a refractory monitoring temperature sensor and a refractory erosion location measuring device suitable for use for the measurement of a temperature of a wide area and for the monitoring of erosion of a lining refractory in a high temperature furnace such as a combustion furnace or a reactor furnace, a refractory vessel for containing and/or conveying a high temperature molten substance such as a hot metal pan, a blast pan, a converter and a metal mixing vessel, a trough for a high temperature molten substance such as a blast furnace main trough and a hot metal furnace trough in the iron industry, or a continuous fusing furnace in various ceramic industries (of glass, cement and so forth).
2. Description of the Prior Art
It is a very important point for the safe operation of a furnace or the like and for the quality control of products to accurately and rapidly detect a temperature condition of a lining refractory of such a high temperature furnace, a refractory vessel, a trough or the like as mentioned above. To this end, various sensors and monitoring devices have been conventionally proposed to monitor a temperature and/or an erosion condition of a refractory.
For example, a multipoint temperature sensor is disclosed in Japanese Utility Model Laid-Open No. 57-170032 wherein a plurality of temperature measuring members each constituted from a sheathed thermocouple, a sheathed temperature measuring resistor or the like are disposed in a jacket protecting tube such that temperature sensing portions thereof are displaced from each other in a longitudinal direction of the jacket protecting tube to permit detection of temperatures at several points. Such sensors are disposed in parallel to a thicknesswise direction of a refractory to detect temperatures at various points so that an amount of erosion of the refractory may be monitored.
Meanwhile, a hot metal trough monitoring method is disclosed in Japanese Patent Laid-Open No. 53-122608 wherein a sensor which can detect a temperature variation as a variation in electric resistance is disposed at a location of a hot metal trough at which the wear of the material is hard such as a connecting point between trough materials and a hot metal surface level. A fixed electric current flow is supplied to the sensor, and a resistance of the sensor is measured. If there is some bleeder or some wear in a trough material, then the temperature at an outer wall portion of the trough rises, and consequently, also the electric resistance of the sensor varies. A possible accident which may arise from a bleeder or wear of the trough by erosion can be prevented by detecting such variation in electric resistance of the sensor.
A hot metal trough monitoring device is disclosed in Japanese Utility Model Publication No. 57-46355 wherein a sensor is embedded in a trough material of a hot metal trough at a location at which an erosion, a crack or the like likely occurs. The sensor is constituted from a tubular conductor and a wire-like conductor extending through the center of the tubular conductor and held in position by an insulating substance filled in the tubular conductor. Then, if a damage such as an erosion or a crack appears in a refractory of the hot metal trough, then the sensor will touch with hot metal and the insulating substance in the sensor may be melted to put the tubular conductor and the wire-like conductor into a mutually conducting condition. A possible accident arising from bleeder or the like can thus be prevented by electrically detecting such conducting condition between the conductors.
An erosion monitoring method for an iron runner of a blast furnace is disclosed in Japanese Patent Laid-Open No. 60-89701 wherein a conductor is embedded in a monolithic refractory at a lower portion of a trough material of an iron runner of a blast furnace, and an ac voltage is applied between a conductor and the ground while a variation in electric current flowing between the conductor and the ground is detected so that erosion of the iron runner is monitored from a detection value of the variation.
The conventional sensors and erosion monitoring means described above, however, individually have the following problems.
In particular, with the sensor disclosed in Japanese Utility Model Laid-Open No. 57-170032, since measurement is conducted by temperature sensing portions of temperature sensing members disposed at a plurality of different points in a longitudinal direction of a jacket protecting tube, only one-dimensional discrete measurement is available, and where there is a hot spot between adjacent such temperature sensing portions, it is impossible to measure such spot. Further, since a large number of sheathed couples or sheathed temperature measuring resistors are accommodated in the jacket protecting tube, the sensor has a comparatively large diameter, which makes it impossible to mount the sensor at a location of a narrow or small spacing. Besides, the sensor has a large bending radius, which makes working and handling of the sensor difficult. Furthermore, where a high temperature above 1,200.degree. C. is to be measured, a high production cost is required for the sensor because a thermocouple of the R type (platinum-platinum rhodium) is normally employed.
Meanwhile, with the monitoring method disclosed in Japanese Patent Laid-Open No. 53-122608, while a resistance variation at 1,200.degree. C. to 1,500.degree. C. or so must be detected in order to detect an abnormal erosion, the variation in resistance of a conductor will be so small in such temperature range that it cannot be detected well. Further, where erosion is monitored over a wide range, the location of such erosion cannot be specified.
With the monitoring device disclosed in Japanese Utility Model Publication No. 57-46355, since an erosion is detected from a melting breakdown of a sensor, the sensor cannot be re-used nor used continuously, and besides, information of an erosion is not obtained until the sensor is melted into a breakdown condition. Also, where erosion is monitored over a wide range, the location of such erosion cannot be specified.
With the monitoring method disclosed in Japanese Patent Laid-Open No. 60-89701, since detection of an erosion is conducted in accordance with point measurement, if it is intended to increase the number of points for measurement, then conductors must necessarily be embedded by such number, which will result in increase in overall size of the arrangement. Further, since a variation in electric resistance when a conductor touches with hot metal is detected, a sensing portion of the sensor can be used only once, and accordingly, the sensor cannot be re-used nor used continuously as in the case of the monitoring device described above. In addition, due to a high temperature of hot metal, a shunt error (deterioration in insulation resistance) of a refractory sometimes occurs, which will cause an error in detection.